1. Field of the Invention
The present invention relates to method and system of lift control of aircraft, and particularly such method and system of lift control of aircraft to generate suitable lift rapidly response to elevators operation.
2. Description of the Related Art
In general, flaps 82 are formed in rear edges of main wings 81 of an airframe 80 of an aircraft, as shown in FIG. 7. The flaps 82 each normally structure portions of the main wings 81.
The flaps 82 are operated to rotate at a suitable angle downward to the main wings from a main wing structuring position to a desired operating position, or rotate upward from the operating position in order to return to the position at which they form a general surface with the main wings 81 when the flaps 82 are operated.
An amount of lift acting on the airframe 80 increases when the flaps 82 are rotated in a downward direction, and the lift decreases when the flaps 82 are rotated in an upward direction. Furthermore, an amount of drag force also increases at the same time when the flaps 82 are operated in the downward direction. The flaps 82 are therefore also operated to rotate in the downward direction in cases when it is necessary to brake the aircraft 80 during flight.
Further, elevators 84 are generally mounted to horizontal tail 83 formed in rear portions of the airframe 80 of the aircraft. The elevators 84 are used in order to point a bow 85 in an upward or downward direction, and are installed in order to perform pitching control of the airframe 80 of the aircraft. The bow 85 therefore rises when a pilot in a cockpit pulls a control stick in a direction toward the rear of the airframe, and the bow 85 drops when the pilot pushes the control stick in a direction toward the front of the aircraft. In other words, the elevators 84 are rotated upward by pulling the control stick backward when the bow 85 is to be raised, and the elevators 84 are rotated downward by pushing forward on the control stick when the bow 85 is to be lowered.
Originally, when an aircraft is made to climb or descend, though depending upon speed of its flight, it takes a predetermined time that the airframe 80 actually climbs or descends after the pilot performs elevators operation by the control stick.
The changes of the attitude of actual airframe in pitching direction after a pilot performs elevators operation by the control stick is explained as an example of airframe 80 climbing in order of a state of the airframe 80 in the process of climb referred to figures.
The pilot first pulls the control stick toward the rear of the airframe and operates the elevators 84 to rotate upward, as shown in FIG. 8 (1). Then, for this elevators operation as shown in FIG. 8 (2), a tail portion 86 of the airframe 86 drops, the bow 85 points upward as a result and the attitude of the airframe 80 becomes upward. The angle of attack of the main wings 81 increases in this case, and the lift generated by airflow from the front becomes larger, as shown in FIG. 8 (3). As a result, the airframe 80 climbs as shown in FIG. 8 (4).
In this case the horizontal tail 83, comprising the elevators 84 of the aircraft, are formed in the tail portion 86 of the airframe. The tail portion 86 of the airframe therefore falls first, and the bow 85 points upward as a result.
Accordingly, when the elevators operation is performed, it takes a predetermined time that the airframe 80 actually climbs or descends after the pilot performs the elevators operation because the aircraft 80 itself has a predetermined length. Further, in order for the airframe 80 to actually begin to climb, one must wait for a predetermined amount of lift to be generated when the bow 85 points upward and the angle of attack of the main wings 81 becomes larger. As a result, it takes a more time.
Therefore although automobiles, for example, are generally structured so that steering is performed in a front end portion of an automobile body by a steering wheel of the front end portion, in comparison time is intrinsically required for the airframe 80 to respond to operations of a rudder upward and downward in the case of aircraft. There is necessity for improvement in the response of the airframe when the elevators operation is performed.
Furthermore, in order to place the aircraft in a landing attitude, procedures such as the following steps relating to aircraft operation are used. Namely, the pilot first operates a throttle lever and descends while increasing or decreasing engine power. Flaps, which are lift control apparatuses mounted to the main wings, are then lowered to a predetermined angle, and the aircraft is decelerated. The elevators of the horizontal tail are then rotated upward by pulling the control stick toward the rear of the aircraft just prior to touchdown, rotating the elevators upward, raising the bow and thereby pulling up the airframe.
Lift is generated in proportion to the square of an airspeed. In this case, at a low speed state during landing, it takes longer time than that in high speed flight until a necessary amount of lift is generated at the main wings after operating the elevators to be upward. The airframe drops greatly during a period until lift is generated, and there are cases in which it is difficult to control the airframe.
It is therefore necessary for a pilot to descend the aircraft by performing the throttle control to increase or decrease the engine power and the raising and lowering operation of the elevators mounted on the horizontal tail during landing. The control of airframe during landing is thus extremely complicated, and this becomes a burden to the pilot in airframe.
Further, when the bow is raised by operating the elevators so as to obtain more lift, the airframe climbs due to the lift generated after a time lag, and there are cases in which an amount of time and distance required for landing is more than necessary.
An object of the present invention is to provide a method of, and a system for, lift control of an aircraft in which a necessary amount of lift corresponding to a pilot""s operation of elevators can easily be obtained.
Further, another object of the present invention is to provide a method of, and a system for, lift control of an aircraft in which an attitude of an airframe in an upward and downward directions can be controlled by conforming with elevators operation by a pilot.
Furthermore, another object of the present invention is to reduce a load required upon a pilot to control an aircraft during landing, when elevators operation is performed by the pilot during landing, by improving ability of response and performing necessary lift control in association with a lift control apparatus by conforming to elevators operation.
The present invention therefore has a structure in which lift control apparatuses such as flaps and flaperons operate in association when elevators operation is performed by a pilot, thus performing lift control rapidly corresponding to pilot""s elevators operation.
Therefore, in accordance with the present invention, lift control apparatuses such as flaps and flaperons operate in association with pilot""s elevators operation, and a necessary amount of lift can be obtained without a time lag. As a result, according to the present invention, ability of response of pitching control with elevators of an aircraft can be greatly improved over conventional pitching control.
In particular, although delicate throttle control and elevators operation have been necessary conventionally in order to avoid an airframe from descending during a period from after elevators operation until lift is generated because speed of the airframe is reduced during landing, a necessary amount of lift can be obtained without a time lag when performing elevators operation in accordance with the present invention. Difficulties in pilot""s control of the airframe during landing can be reduced, and a safer landing can be achieved.
The present invention is therefore a method of lift control of an aircraft by controlling lift acting upon the aircraft based on a state of elevators operation. Lift control apparatuses operate in association based on the a state of the elevators operation, and lift corresponding to the flying state of an airframe is obtained.
As a result, ability of response of the steering control of an aircraft in vertical motion is improved because a desired amount of lift can be obtained by the lift control apparatuses in response to elevators operation, and preferred airframe operation can be realized in accordance with the present invention.
Further, another aspect of the present invention is that when the elevators are operated in order to climb, the amount of lift is controlled with the lift control apparatuses so as to increase, and when the elevators are operated in order to descend, the amount of lift is controlled with the lift control apparatuses so as to decrease.
Attitude control of an airframe in the vertical motion can therefore be easily and quickly performed in accordance with the present invention because lift in both an increasing direction and in a decreasing direction can be obtained with the lift control apparatuses in accordance with the pilot""s elevators operation.
In addition, another aspect of the present invention is that an operation amount in a direction for increasing the lift of the lift control apparatuses is controlled so as to become smaller in accordance with the airframe speed becoming lower, and is controlled so as to become smaller in accordance with the airframe speed becoming higher.
Another aspect of the present invention is that it is structured so that control in a direction increasing the lift of the lift control apparatuses is not performed in cases in which there is a possibility of an airframe stalling when performing the aforementioned control when aircraft speed is low.
Another aspect of the present invention is that it is structured so that control in directions for increasing or decreasing the amount of lift of the lift control apparatuses is not performed when the aircraft speed is high.
If the lift control apparatuses operate and increase the amount of lift, drag force acting on the airframe increases at the same time. From a standpoint of ensuring safety of the airframe, an amount of operation of the lift control apparatuses is controlled so as to gradually become smaller as speed decreases when the aircraft speed is low. Furthermore, there is a danger of stalling if the lift control apparatuses operate when the speed of the aircraft is lower than a predetermined speed. It is structured such that operation of the lift control apparatuses is controlled so as not to be performed if there is the possibility of stalling.
Further, when an aircraft is flying at a speed which is greater than a predetermined speed, then lift control with the lift control apparatuses in association with the elevators operation is unnecessary because lift is proportional to the square of the velocity and a necessary lift can be obtained without a large time lag. The operation amount so as to increase or decrease the lift of the lift control apparatuses is controlled so as to become smaller in accordance with the airframe speed becoming larger.
In addition, when the speed of an aircraft reaches or exceeds a fixed speed, then lift can be obtained without a time lag in cases where this type of lift control is performed, and therefore smooth flight is inhibited. The present invention is thus structured such that lift control is not performed in association with elevators operation for cases in which the speed of the airframe is equal to or higher than a fixed speed.
Another aspect of the present invention is that, during landing of the aircraft, the lift control apparatuses are reset by being controlled so as to increase lift when the elevators are operated for climb after the lift control apparatuses are set in a predetermined angular state. In addition, when the elevators are operated for descent, then the lift control apparatuses are reset by being controlled so as to decrease lift.
In general, during landing of an aircraft, a pilot first operates lift control apparatuses such as flaps by a predetermined amount, lowering the flight speed, and then operates elevators to lift up a bow. Next, throttle operation and elevators operation by using a control stick is performed, regulating the descent speed of the airframe and its descent attitude, and thereby performing touchdown.
The present invention is structured such that the lift control apparatuses operate in association with the elevators, and therefore the lift control apparatuses initially set by the pilot are then reset later so that lift increases in association with the pilot operating the elevators for climb. In other words, it is structured such that, when the aircraft enters on a landing phase, the flaps which are first set to a predetermined angle by the pilot are then moved to a higher angle position due to the elevators being operated upward, and the necessary amount of lift accompanying the bow being raised by operating the elevators upward is obtained.
Similarly, it is structured such that, after initially setting the lift control apparatuses when the aircraft enters on the landing phase, necessary lift control accompanying the bow being lowered is performed when the elevators are operated so as to descend in order to perform the pitching control of the airframe.
As a result, it is not necessary for the pilot to descend while performing attitude control of the airframe by only operating the throttles and elevators because the necessary amount of lift can be obtained with the present invention when the elevators are operated without the time lag found conventionally. It thus becomes possible to increase stability and to reduce a load required upon a pilot to control an airframe during landing.
Another aspect of the present invention is that angular position of the lift control apparatuses set by the pilot are detected along with an operation state when the elevators are operated by the pilot. Information relating to the angular position of the lift control apparatuses, information relating to the elevators operation state, and information on the speed of the airframe are taken as a basis, and information relating to a correlation between the aircraft speed and the amount of operation of the lift control apparatuses are referenced, and the amount of operation of the lift control apparatuses is determined.
The angular position of the lift control apparatuses is are detected by, for example, detecting the state in which the flaps indicator switch formed inside a cockpit is set with a predetermined sensor. Further, information relating to the elevators operation may be an amount of elevators operation, and it may be a speed of elevators operation. In addition, it may be structured such that the lift control apparatuses is controlled on the basis of the amount of elevators operation and the speed of elevators operation.
The amount of elevators operation is calculated by detecting an amount of control stick operation, and the amount of lift control apparatus operation is determined in proportion to the amount of elevators operation. Further, the amount of lift control apparatus operation is determined based upon the speed of elevators operation by detecting the elevators operation speed. By operating the lift control apparatuses based upon the speed of elevators operation, the lift control apparatuses can be operated and the necessary amount of lift can be immediately obtained when elevators operation begins due to the control stick operated by the pilot. More real-time lift generation conforming to elevators operation can thus be made possible.
In this case, the amount of elevators operation can be detected by sensors mounted in the control stick for detecting the amount of elevators operation of the control stick. Further, the elevators operation speed is calculated by, for example, always detecting the amount of elevators operation at predetermined intervals of time (for example, approximately {fraction (1/100)} second), finding the difference between the amount of elevators operation at the present detection point with the amount of elevators operation at the previous detection point, and dividing the numerical value of the difference by the length of the time interval of the detection.
Furthermore, it becomes necessary to consider the speed of the airframe at this point for operation control of the lift control apparatuses because lift is generated proportional to the square of the velocity. The airframe speed in this case may be the airspeed in this case. The airspeed may be measured by a Pitot static tube mounted to the airframe.
Further, in the present invention an ECU used in this lift control stores in advance a map for obtaining the necessary amount of lift. The map is composed of a graph relating to airframe speed information and the amount of lift control apparatuses operation necessary at the airframe speed. The initial graph is referenced based on data relating to the detected airframe speed, the initially set flaps indicator position, and the state of elevators operation, and the amount of operation of the lift control apparatuses is determined.
Another aspect of the present invention is that it is provided with: a step of detecting an indicator position at the point for the lift control apparatuses; a step of detecting airframe speed; a step of detecting the amount of elevators operation; a step of detecting the speed of elevators operation; a step of judging whether to perform control of the lift control apparatuses in association with the elevators operation so that the lift increases, or so that the lift decreases; a step of determining a command value for controlling the lift control apparatuses based on the amount of elevators operation; and a step of determining a command value for controlling the lift control apparatuses based on the speed of elevators operation.
Further, another aspect of the present invention is that it is structured having: a step of detecting a stall warning signal from a stall warning apparatus that emits a warning in case there is a possibility that the airframe may stall if the angle of attack of the airframe becomes equal to or larger than a predetermined angle; and a step of judging whether or not the stall warning signal has been detected. Operation of the lift control apparatuses in a direction for increasing lift is not performed in cases in which the stall warning signal is detected.
This is done if there is a possibility of stalling in order to avoid a situation in which the danger of stalling is made even greater because the amount of drag force increases at the same time as the lift control apparatuses are operated in a direction for increasing lift.
Further, another aspect of the present invention is that the elevators operation amount and operation speed are detected based upon operating a control stick mounted in a cockpit.
Furthermore, the lift control apparatuses may be flaps, and further they may also be flaperons. Flaperons are lift control apparatuses prepared on the main wings of an airframe and function as flaps and at the same time also play a role as ailerons.
Further, another aspect of the present invention is that it is a lift control system for an aircraft and structured as follows. A lift control system is provided with: a lift control apparatus operating portion capable of suitably setting lift control apparatuses so as to obtain a predetermined amount of lift for an airframe; speed sensors for detecting airspeed; and a driver apparatus for driving the lift control apparatuses based upon commands from the lift control apparatuses operating portion. The present invention is provided with elevators operation state detection sensors capable of detecting the elevators operation state by a control stick mounted in a cockpit, and has a map relating to a correlation between airframe speed and amount of operation of the lift control apparatuses in order to obtain a necessary amount of lift. Information relating to the elevators operation state obtained by the elevators operation state detection sensors, and information relating to the airframe speed is taken as a basis, the map is referenced, and an operation amount for the lift control apparatuses is obtained. The lift control apparatuses are operated by the driver apparatus based on the operation amount obtained.
In this case, the information relating to the elevators operation state may be the amount of elevators operation in accordance with the control stick, it may be the speed of elevators operation in accordance with the control stick, and in addition, it may be the amount of elevators operation and the speed of elevators operation due to the control stick.
Furthermore, another aspect of the present invention is that it is provided with a stall warning apparatus that emits a warning in case there is a possibility of an airframe stalling because the angle of attack of the airframe is equal to or greater than a predetermined angle at a given speed. When the stall warning apparatus operates, then operation of the lift control apparatuses in a direction for increasing lift is prohibited.